This invention relates to fluid motors, and more particularly to a motor driven by inlet fluid pressure operating through peristaltic tubes.
Peristaltic pumps are known in which fluid is moved through the flexible tubes in a manner simulating the peristaltic movement through the human digestive system. Typically, a roller travels along the length of the peristaltic tube and collapses the tube between the roller and a support to thereby force material in the tube from the inlet to an outlet. An example of such a peristaltic pump is found in U.S. Pat. No. 3,358,609 issued Dec. 19, 1967 to Worth, et al.
The use of peristaltic movement of fluids through flexible tubes to drive the output of a fluid motor is much less well known. Examples of such fluid motors are found in the following U.S. patents:
U.S. Pat. No. 2,864,341 issued Dec. 16, 1958 to Novak in which an output pin is driven in an arc defined by a rigid annular ring that contains the flexible tube and roller;
U.S. Pat. No. 3,039,442 issued June 19, 1962 to Hornschuch, et al. in which a series of expansible membranes are located about the inner perimeter of a stator and rollers projecting from a rotor mounted on a motor shaft travel along the inner peripheries of the membranes; and
U.S. Pat. No. 4,576,242 issued Mar. 18, 1986 to Mundell which is similar in concept to the U.S. Pat. No. 3,039,442.
The flexible tube is a principal wear element of any peristaltic pump or motor. In addition to being constantly subjected to squeezing by the action of the rollers, the tube must also carry the pressure of the fluid moving through it. The forces on the tube are particularly pronounced in a fluid motor application because of the need to use relatively high fluid pressures in order to obtain acceptable work output on the motor shaft. The U.S. Pat. No. 4,576,242 attempts to equalize the pressure within and without the tube by the use of a separate external fluid lubricant and a pressure equalizing unit.
I have developed a peristaltic motor of simple construction in which the forces on the flexible tubes are held to a minimum and in which the output to the motor shaft is smooth and non-cyclical.